Proof of concept with totp

1 files changed, 30 insertions, 0 deletions

diff --git a/src/totp.rs b/src/totp.rs
new file mode 100644
index 0000000..09b4503
--- /dev/null
+++ b/src/totp.rs
@@ -0,0 +1,30 @@
+use oath::totp_custom_time;
+use oath::HashType;
+use std::time::{UNIX_EPOCH, SystemTime};
+
+pub fn verify(secret: &str, token: &str) -> Result<bool, &'static str> {
+    let time_step = 30;
+    let totp = |time| {
+        totp_custom_time(secret, 6, 0, time_step, time, &HashType::SHA512)
+            .map(|t| {
+                debug!("Generated OTP for probing {} for key {}", t, secret);
+                t
+            })
+            .map(|t| format!("{:06}", t) == *token)
+    };
+    let current_time: u64 = SystemTime::now().duration_since(UNIX_EPOCH)
+        .expect("Earlier than 1970-01-01 00:00:00 UTC").as_secs();
+    if current_time % time_step <= 5 && totp(current_time - 30)? {
+        return Ok(true);
+    }
+
+    if current_time % time_step >= 25 && totp(current_time + 30)? {
+        return Ok(true);
+    }
+
+    if totp(current_time)? {
+        return Ok(true);
+    }
+
+    Ok(false)
+}
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